xbar.cc revision 9294
1/* 2 * Copyright (c) 2011-2012 ARM Limited 3 * All rights reserved 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2006 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Ali Saidi 41 * Andreas Hansson 42 * William Wang 43 */ 44 45/** 46 * @file 47 * Definition of a bus object. 48 */ 49 50#include "base/misc.hh" 51#include "base/trace.hh" 52#include "debug/Bus.hh" 53#include "debug/BusAddrRanges.hh" 54#include "debug/Drain.hh" 55#include "mem/bus.hh" 56 57BaseBus::BaseBus(const BaseBusParams *p) 58 : MemObject(p), 59 headerCycles(p->header_cycles), width(p->width), 60 gotAddrRanges(p->port_default_connection_count + 61 p->port_master_connection_count, false), 62 gotAllAddrRanges(false), defaultPortID(InvalidPortID), 63 useDefaultRange(p->use_default_range), 64 blockSize(p->block_size) 65{} 66 67BaseBus::~BaseBus() 68{ 69 for (MasterPortIter m = masterPorts.begin(); m != masterPorts.end(); 70 ++m) { 71 delete *m; 72 } 73 74 for (SlavePortIter s = slavePorts.begin(); s != slavePorts.end(); 75 ++s) { 76 delete *s; 77 } 78} 79 80void 81BaseBus::init() 82{ 83 // determine the maximum peer block size, look at both the 84 // connected master and slave modules 85 uint32_t peer_block_size = 0; 86 87 for (MasterPortConstIter m = masterPorts.begin(); m != masterPorts.end(); 88 ++m) { 89 peer_block_size = std::max((*m)->peerBlockSize(), peer_block_size); 90 } 91 92 for (SlavePortConstIter s = slavePorts.begin(); s != slavePorts.end(); 93 ++s) { 94 peer_block_size = std::max((*s)->peerBlockSize(), peer_block_size); 95 } 96 97 // if the peers do not have a block size, use the default value 98 // set through the bus parameters 99 if (peer_block_size != 0) 100 blockSize = peer_block_size; 101 102 // check if the block size is a value known to work 103 if (blockSize != 16 || blockSize != 32 || blockSize != 64 || 104 blockSize != 128) 105 warn_once("Block size is neither 16, 32, 64 or 128 bytes.\n"); 106} 107 108BaseMasterPort & 109BaseBus::getMasterPort(const std::string &if_name, PortID idx) 110{ 111 if (if_name == "master" && idx < masterPorts.size()) { 112 // the master port index translates directly to the vector position 113 return *masterPorts[idx]; 114 } else if (if_name == "default") { 115 return *masterPorts[defaultPortID]; 116 } else { 117 return MemObject::getMasterPort(if_name, idx); 118 } 119} 120 121BaseSlavePort & 122BaseBus::getSlavePort(const std::string &if_name, PortID idx) 123{ 124 if (if_name == "slave" && idx < slavePorts.size()) { 125 // the slave port index translates directly to the vector position 126 return *slavePorts[idx]; 127 } else { 128 return MemObject::getSlavePort(if_name, idx); 129 } 130} 131 132Tick 133BaseBus::calcPacketTiming(PacketPtr pkt) 134{ 135 // determine the current time rounded to the closest following 136 // clock edge 137 Tick now = nextCycle(); 138 139 Tick headerTime = now + headerCycles * clock; 140 141 // The packet will be sent. Figure out how long it occupies the bus, and 142 // how much of that time is for the first "word", aka bus width. 143 int numCycles = 0; 144 if (pkt->hasData()) { 145 // If a packet has data, it needs ceil(size/width) cycles to send it 146 int dataSize = pkt->getSize(); 147 numCycles += dataSize/width; 148 if (dataSize % width) 149 numCycles++; 150 } 151 152 // The first word will be delivered after the current tick, the delivery 153 // of the address if any, and one bus cycle to deliver the data 154 pkt->firstWordTime = headerTime + clock; 155 156 pkt->finishTime = headerTime + numCycles * clock; 157 158 return headerTime; 159} 160 161template <typename PortClass> 162BaseBus::Layer<PortClass>::Layer(BaseBus& _bus, const std::string& _name, 163 Tick _clock) : 164 bus(_bus), _name(_name), state(IDLE), clock(_clock), drainEvent(NULL), 165 releaseEvent(this) 166{ 167} 168 169template <typename PortClass> 170void BaseBus::Layer<PortClass>::occupyLayer(Tick until) 171{ 172 // ensure the state is busy or in retry and never idle at this 173 // point, as the bus should transition from idle as soon as it has 174 // decided to forward the packet to prevent any follow-on calls to 175 // sendTiming seeing an unoccupied bus 176 assert(state != IDLE); 177 178 // note that we do not change the bus state here, if we are going 179 // from idle to busy it is handled by tryTiming, and if we 180 // are in retry we should remain in retry such that 181 // succeededTiming still sees the accurate state 182 183 // until should never be 0 as express snoops never occupy the bus 184 assert(until != 0); 185 bus.schedule(releaseEvent, until); 186 187 DPRINTF(BaseBus, "The bus is now busy from tick %d to %d\n", 188 curTick(), until); 189} 190 191template <typename PortClass> 192bool 193BaseBus::Layer<PortClass>::tryTiming(PortClass* port) 194{ 195 // first we see if the bus is busy, next we check if we are in a 196 // retry with a port other than the current one 197 if (state == BUSY || (state == RETRY && port != retryList.front())) { 198 // put the port at the end of the retry list 199 retryList.push_back(port); 200 return false; 201 } 202 203 // update the state which is shared for request, response and 204 // snoop responses, if we were idle we are now busy, if we are in 205 // a retry, then do not change 206 if (state == IDLE) 207 state = BUSY; 208 209 return true; 210} 211 212template <typename PortClass> 213void 214BaseBus::Layer<PortClass>::succeededTiming(Tick busy_time) 215{ 216 // if a retrying port succeeded, also take it off the retry list 217 if (state == RETRY) { 218 DPRINTF(BaseBus, "Remove retry from list %s\n", 219 retryList.front()->name()); 220 retryList.pop_front(); 221 state = BUSY; 222 } 223 224 // we should either have gone from idle to busy in the 225 // tryTiming test, or just gone from a retry to busy 226 assert(state == BUSY); 227 228 // occupy the bus accordingly 229 occupyLayer(busy_time); 230} 231 232template <typename PortClass> 233void 234BaseBus::Layer<PortClass>::failedTiming(PortClass* port, Tick busy_time) 235{ 236 // if we are not in a retry, i.e. busy (but never idle), or we are 237 // in a retry but not for the current port, then add the port at 238 // the end of the retry list 239 if (state != RETRY || port != retryList.front()) { 240 retryList.push_back(port); 241 } 242 243 // even if we retried the current one and did not succeed, 244 // we are no longer retrying but instead busy 245 state = BUSY; 246 247 // occupy the bus accordingly 248 occupyLayer(busy_time); 249} 250 251template <typename PortClass> 252void 253BaseBus::Layer<PortClass>::releaseLayer() 254{ 255 // releasing the bus means we should now be idle 256 assert(state == BUSY); 257 assert(!releaseEvent.scheduled()); 258 259 // update the state 260 state = IDLE; 261 262 // bus is now idle, so if someone is waiting we can retry 263 if (!retryList.empty()) { 264 // note that we block (return false on recvTiming) both 265 // because the bus is busy and because the destination is 266 // busy, and in the latter case the bus may be released before 267 // we see a retry from the destination 268 retryWaiting(); 269 } else if (drainEvent) { 270 DPRINTF(Drain, "Bus done draining, processing drain event\n"); 271 //If we weren't able to drain before, do it now. 272 drainEvent->process(); 273 // Clear the drain event once we're done with it. 274 drainEvent = NULL; 275 } 276} 277 278template <typename PortClass> 279void 280BaseBus::Layer<PortClass>::retryWaiting() 281{ 282 // this should never be called with an empty retry list 283 assert(!retryList.empty()); 284 285 // we always go to retrying from idle 286 assert(state == IDLE); 287 288 // update the state which is shared for request, response and 289 // snoop responses 290 state = RETRY; 291 292 // note that we might have blocked on the receiving port being 293 // busy (rather than the bus itself) and now call retry before the 294 // destination called retry on the bus 295 retryList.front()->sendRetry(); 296 297 // If the bus is still in the retry state, sendTiming wasn't 298 // called in zero time (e.g. the cache does this) 299 if (state == RETRY) { 300 retryList.pop_front(); 301 302 //Burn a cycle for the missed grant. 303 304 // update the state which is shared for request, response and 305 // snoop responses 306 state = BUSY; 307 308 // determine the current time rounded to the closest following 309 // clock edge 310 Tick now = bus.nextCycle(); 311 312 occupyLayer(now + clock); 313 } 314} 315 316template <typename PortClass> 317void 318BaseBus::Layer<PortClass>::recvRetry() 319{ 320 // we got a retry from a peer that we tried to send something to 321 // and failed, but we sent it on the account of someone else, and 322 // that source port should be on our retry list, however if the 323 // bus layer is released before this happens and the retry (from 324 // the bus point of view) is successful then this no longer holds 325 // and we could in fact have an empty retry list 326 if (retryList.empty()) 327 return; 328 329 // if the bus layer is idle 330 if (state == IDLE) { 331 // note that we do not care who told us to retry at the moment, we 332 // merely let the first one on the retry list go 333 retryWaiting(); 334 } 335} 336 337PortID 338BaseBus::findPort(Addr addr) 339{ 340 // we should never see any address lookups before we've got the 341 // ranges of all connected slave modules 342 assert(gotAllAddrRanges); 343 344 // Check the cache 345 PortID dest_id = checkPortCache(addr); 346 if (dest_id != InvalidPortID) 347 return dest_id; 348 349 // Check the address map interval tree 350 PortMapConstIter i = portMap.find(addr); 351 if (i != portMap.end()) { 352 dest_id = i->second; 353 updatePortCache(dest_id, i->first); 354 return dest_id; 355 } 356 357 // Check if this matches the default range 358 if (useDefaultRange) { 359 if (defaultRange == addr) { 360 DPRINTF(BusAddrRanges, " found addr %#llx on default\n", 361 addr); 362 return defaultPortID; 363 } 364 } else if (defaultPortID != InvalidPortID) { 365 DPRINTF(BusAddrRanges, "Unable to find destination for addr %#llx, " 366 "will use default port\n", addr); 367 return defaultPortID; 368 } 369 370 // we should use the range for the default port and it did not 371 // match, or the default port is not set 372 fatal("Unable to find destination for addr %#llx on bus %s\n", addr, 373 name()); 374} 375 376/** Function called by the port when the bus is receiving a range change.*/ 377void 378BaseBus::recvRangeChange(PortID master_port_id) 379{ 380 // remember that we got a range from this master port and thus the 381 // connected slave module 382 gotAddrRanges[master_port_id] = true; 383 384 // update the global flag 385 if (!gotAllAddrRanges) { 386 // take a logical AND of all the ports and see if we got 387 // ranges from everyone 388 gotAllAddrRanges = true; 389 std::vector<bool>::const_iterator r = gotAddrRanges.begin(); 390 while (gotAllAddrRanges && r != gotAddrRanges.end()) { 391 gotAllAddrRanges &= *r++; 392 } 393 } 394 395 // note that we could get the range from the default port at any 396 // point in time, and we cannot assume that the default range is 397 // set before the other ones are, so we do additional checks once 398 // all ranges are provided 399 DPRINTF(BusAddrRanges, "received RangeChange from slave port %s\n", 400 masterPorts[master_port_id]->getSlavePort().name()); 401 402 if (master_port_id == defaultPortID) { 403 // only update if we are indeed checking ranges for the 404 // default port since the port might not have a valid range 405 // otherwise 406 if (useDefaultRange) { 407 AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges(); 408 409 if (ranges.size() != 1) 410 fatal("Bus %s may only have a single default range", 411 name()); 412 413 defaultRange = ranges.front(); 414 } 415 } else { 416 // the ports are allowed to update their address ranges 417 // dynamically, so remove any existing entries 418 if (gotAddrRanges[master_port_id]) { 419 for (PortMapIter p = portMap.begin(); p != portMap.end(); ) { 420 if (p->second == master_port_id) 421 // erasing invalidates the iterator, so advance it 422 // before the deletion takes place 423 portMap.erase(p++); 424 else 425 p++; 426 } 427 } 428 429 AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges(); 430 431 for (AddrRangeConstIter r = ranges.begin(); r != ranges.end(); ++r) { 432 DPRINTF(BusAddrRanges, "Adding range %#llx : %#llx for id %d\n", 433 r->start, r->end, master_port_id); 434 if (portMap.insert(*r, master_port_id) == portMap.end()) { 435 PortID conflict_id = portMap.find(*r)->second; 436 fatal("%s has two ports with same range:\n\t%s\n\t%s\n", 437 name(), 438 masterPorts[master_port_id]->getSlavePort().name(), 439 masterPorts[conflict_id]->getSlavePort().name()); 440 } 441 } 442 } 443 444 // if we have received ranges from all our neighbouring slave 445 // modules, go ahead and tell our connected master modules in 446 // turn, this effectively assumes a tree structure of the system 447 if (gotAllAddrRanges) { 448 // also check that no range partially overlaps with the 449 // default range, this has to be done after all ranges are set 450 // as there are no guarantees for when the default range is 451 // update with respect to the other ones 452 if (useDefaultRange) { 453 for (PortID port_id = 0; port_id < masterPorts.size(); ++port_id) { 454 if (port_id == defaultPortID) { 455 if (!gotAddrRanges[port_id]) 456 fatal("Bus %s uses default range, but none provided", 457 name()); 458 } else { 459 AddrRangeList ranges = 460 masterPorts[port_id]->getAddrRanges(); 461 462 for (AddrRangeConstIter r = ranges.begin(); 463 r != ranges.end(); ++r) { 464 // see if the new range is partially 465 // overlapping the default range 466 if (r->intersects(defaultRange) && 467 !r->isSubset(defaultRange)) 468 fatal("Range %#llx : %#llx intersects the " \ 469 "default range of %s but is not a " \ 470 "subset\n", r->start, r->end, name()); 471 } 472 } 473 } 474 } 475 476 // tell all our neighbouring master ports that our address 477 // ranges have changed 478 for (SlavePortConstIter s = slavePorts.begin(); s != slavePorts.end(); 479 ++s) 480 (*s)->sendRangeChange(); 481 } 482 483 clearPortCache(); 484} 485 486AddrRangeList 487BaseBus::getAddrRanges() const 488{ 489 // we should never be asked without first having sent a range 490 // change, and the latter is only done once we have all the ranges 491 // of the connected devices 492 assert(gotAllAddrRanges); 493 494 DPRINTF(BusAddrRanges, "received address range request, returning:\n"); 495 496 // start out with the default range 497 AddrRangeList ranges; 498 ranges.push_back(defaultRange); 499 DPRINTF(BusAddrRanges, " -- %#llx : %#llx DEFAULT\n", 500 defaultRange.start, defaultRange.end); 501 502 // add any range that is not a subset of the default range 503 for (PortMapConstIter p = portMap.begin(); p != portMap.end(); ++p) { 504 if (useDefaultRange && p->first.isSubset(defaultRange)) { 505 DPRINTF(BusAddrRanges, " -- %#llx : %#llx is a SUBSET\n", 506 p->first.start, p->first.end); 507 } else { 508 ranges.push_back(p->first); 509 DPRINTF(BusAddrRanges, " -- %#llx : %#llx\n", 510 p->first.start, p->first.end); 511 } 512 } 513 514 return ranges; 515} 516 517unsigned 518BaseBus::deviceBlockSize() const 519{ 520 return blockSize; 521} 522 523template <typename PortClass> 524unsigned int 525BaseBus::Layer<PortClass>::drain(Event * de) 526{ 527 //We should check that we're not "doing" anything, and that noone is 528 //waiting. We might be idle but have someone waiting if the device we 529 //contacted for a retry didn't actually retry. 530 if (!retryList.empty() || state != IDLE) { 531 DPRINTF(Drain, "Bus not drained\n"); 532 drainEvent = de; 533 return 1; 534 } 535 return 0; 536} 537 538/** 539 * Bus layer template instantiations. Could be removed with _impl.hh 540 * file, but since there are only two given options (MasterPort and 541 * SlavePort) it seems a bit excessive at this point. 542 */ 543template class BaseBus::Layer<SlavePort>; 544template class BaseBus::Layer<MasterPort>; 545